1. Field of the Invention
This invention relates generally to a rotating unit, and more specifically to a rotating unit constructed so that a rotating wheel is driven by a drive motor through the use of a reduction gear mechanism wherein the reduction gear mechanism is simplified to reduce the size and weight of the mechanism by forming a gear on the internal circumference of the rotating wheel, and the rotating shafts of the rotating wheel and the drive motor are adapted to be in alignment with each other.
2. Description of the Prior Art
In most devices for driving a rotating wheel through the use of a reduction gear mechanism, the rotating axes of the drive motor and the rotating wheel are usually not in alignment with each other. Particularly, in a simplified reduction gear mechanism with reduced number of gears, the distance between the rotating shafts of the rotating wheel and the drive motor tends to increase. The increased distance between the rotating shafts results in an increase in the size of the reduction gear mechanism. To reduce the size of the rotating unit, therefore, it is desirable to make the rotating axes of the rotating wheel and the drive motor in alignment with each other. To attain this, a reduction gear device using planetary gears has often been used. The planetary gear type reduction gear devices, however, have problems such as wear of the planetary gears and higher cost. Particularly, for use in a model airplane, a small-sized, light and inexpensive rotating unit the gravity center of which is located as near as possible the extension of the rotating axis of the rotated member is desired.